<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			span{
				border:2px solid red;
				/* outline-width:4px;
				 outline-color:bluel;
				 outline-style:dashed;*/
				 outline:4px green dashed;
			}
			.username{
				border:1px solid red;
				outline:none;
				/* 不设置轮廓 */
				paadding-left:3px;
				width:80px;
			}
			.email{
				border:0;
				outline:0;
				border-bottom:1px solid #000;
			}
			.btnSubmit{
				border:0;
				padding:5px;
				width:100px;
			}
			.mydiv{
				width:100px;
				background:#ccc;
				border:2px solid red;
				/* outline:2px solid red; */
			}
		</style>
	</head>
	<body>
		<span>welcome to css</span>
		<hr>
		
		用户名：<input type="text" class="username">
		<a href="#">CSS</a>
		<hr>
		
		邮箱：<input type="text" class="email">
		<input type="submit" value="提交" class="btnSubmit">
		<hr>
		
		<div class="mydiv">div</div>
	</body>
</html>
